Quicksort implementation for Sybase Aleri (SPLASH)

quicksort.xmlf

// Pretty literal implementation of the quick sort documented on Wikipedia
// http://en.wikipedia.org/wiki/Quicksort
// Datatypes can trivially be changed to others

int32 quicksort_double (vector(double) data) {
  quicksort_internal_double (data, 0, size(data) - 1);
}

int32 quicksort_internal_double (vector(double) data, int32 vleft, int32 vright) {
  if (vright > vleft) {
    int32 pivotIndex := (vleft + vright) / 2;
    int32 pivotNewIndex := partition_double (data, vleft, vright, pivotIndex);
    quicksort_internal_double (data, vleft, pivotNewIndex - 1);
    quicksort_internal_double (data, pivotNewIndex + 1, vright);
  }
}

int32 partition_double (vector(double) data, int32 vleft, int32 vright, int32 pivotIndex) {
  double pivotValue := data[pivotIndex];
  swap_double(data, pivotIndex, vright);
  int32 storeIndex := vleft;
  int32 i := vleft;
  while (i < vright) {
    if (data[i] <= pivotValue) {
      swap_double (data, i, storeIndex);
      storeIndex++;
    }
    i++;
  }
  swap_double (data, storeIndex, vright);
  return storeIndex;
}

int32 swap_double (vector(double) data, int32 el1, int32 el2) {
  double temp := data[el1];
  data[el1] := data[el2];
  data[el2] := temp;
}